Measurement Uncertainty in the Evaluation of Hand-Arm Vibration Exposure in the Workplace - an Introduction to Iso 5349-2 (original) (raw)
The Development and Use of Tools to Support Workplace Hand-Arm Vibration Exposure Evaluation
Acoustics Australia, 2016
Long-term exposure to hand-arm vibration (HAV) from powered machinery is known to be responsible for damage to the hand and arm. To protect workers, employers are required to apply appropriate measures to control vibration exposures. A key part of the process of effective assessment and control of vibration risks is the evaluation of vibration exposures. The vibration data required for exposure evaluation need to be suitable and sufficient to enable the appropriate actions to be taken. In Great Britain, the Health and Safety Executive (HSE) has provided tools designed to simplify exposure evaluation as part of employers' risk assessments for vibration. These tools help to demystify the process and help employers move as quickly as possible from the evaluation of exposures to actively controlling risk. This paper discusses the tools provided by HSE designed to support the HAV risk assessment process. It reviews existing tools including the "rule of thumb", which provides an initial indicator to likely risks, and the points system and calculator tool, which simplify the exposure calculation processes. The paper also introduces a table of indicative vibration magnitudes, which has been developed for a revision of HSE guidance to help employers to achieve initial estimates of likely vibration exposures. The objective of all these tools is to enable employers to get efficiently from risk assessment to making decisions about the requirements for vibration control and getting those controls implemented.
Uncertainty in the evaluation of occupational exposure to whole-body vibration
Journal of Sound and Vibration, 2006
Uncertainties associated with field assessments of daily exposure to whole-body vibration (WBV) have been investigated in four categories of work vehicles (fork lift trucks, wheel loaders, garbage trucks, buses) in different working conditions. A total of 50 vehicles were included in the study. WBV exposures were measured in different field conditions in marble quarries, marble laboratories, dockyards, paper mills, transportation and public utilities: over 700 individual vibration measurements were analysed to quantify relevant uncertainty components due to changes in the operators' working methods, variations in the characteristics and conditions of the machines, changes in the characteristics of the travelling surface, uncertainty in the evaluation of exposure duration, and systematic errors due to measurement equipment. The methods used in the study to calculate measurement uncertainties are in accordance with the ISO publication ''Guide to the Expression of Uncertainty in Measurement''. The study made it possible to isolate major sources of uncertainty in field assessment of daily exposures to WBV. The investigation revealed that, in all the field conditions, differences in the characteristics of the machines and/or in working cycles were the most relevant uncertainty components. The overall relative uncertainty p in WBV field assessment was in the range 14% opo32%, whereas the relative uncertainty caused by transducer and measurement equipment in a correctly calibrated system is less than 4%. r
Comparison of different measures for hand–arm vibration exposure
Safety Science, 1998
Vibration measurements have been done on hand-held tools in a group of 48 platers by evaluating the individual vibration acceleration and absorption of vibration energy. The measurement of the acceleration has been done frequency-weighted and frequency-unweighted Ž. in accordance with ISO 5349 and NIOSH USA recommendations for hand-arm vibration standards, respectively. The acceleration and the energy absorption have been measured simultaneously in the three orthogonal directions, the latter by using a specially designed adapter. The exposure time has been determined by both subjective assessments and objective measurements. Individual energy-equivalent accelerations and vibration dosages have been calculated from these data. The results show that the type of tool was critical to vibration load intensity when the different measures for determining vibration levels were used. Of the methods used, the evaluation specified by ISO 5349 makes most consideration of low Ž. Ž frequencies of vibration-50 Hz , absorption of vibration energy middle frequencies 50-200. Ž. Hz and NIOSH of high frequencies) 200 Hz. The results show a poor correlation between the three methods used. The same was found between mean subjective assessment and objective measurement of the average exposure time. Further studies of the relation between results presented here and generated disturbance will be conducted, which may clarify any exposureresponse relationship.
Assessment of the Uncertainty in Human Exposure to Vibration: An Experimental Study
IEEE Sensors Journal, 2000
The purpose of this paper is to analyze and to quantify the contributions of measurement uncertainty in the human exposure to vibrations. Typically, the high-level vibrations exposure in workplace can cause the onset of pathologies affecting musculoskeletal, vascular, and neurological systems. Regulations and standards lay down the assessment of the health risks arising from vibrations using specific instruments and a proper measurement procedure. This paper proposes a methodology for the uncertainty evaluation of exposure to hand-arm and wholebody vibrations; as a main contribution, the uncertainty analysis of daily exposure hand-arm vibrations and whole-body vibrations is provided to estimate the vibrations exposition and to reduce the risks of the worker. This activity was developed in collaboration with Military Navy Arsenalin Taranto (South Italy), which is active all along in the protection of health and the safety in the workplace.
Evaluation of hand-transmitted vibration exposure on basis of a questionnaire
The Journal of the Acoustical Society of America, 2008
The implementation of European directive 2002/44/EC has raised the question also in Finland about the current exposure to hand-arm vibration (HAV) and its consequences on workers' health. In this study we collected data on different worker groups in metal and aircraft industry by a questionnaire about their exposure to HAV and symptoms of upper extremities. We found that the more the workers were exposed to HAV the more they reported finger blanching, numbness and tingling of fingers in cold and musculoskeletal symptoms of upper extremities. The distribution of symptoms of a group exposed to impulsive vibration was strikingly different. The results indicate that a short compact questionnaire can be recommended to screen the exposure to HAV and health effects of HAV at a workplace.
Determination of hand-transmitted vibration risk on the human
International Journal of Industrial Ergonomics, 2019
The purpose of this paper is to examine the effectiveness of the proposed consideration for handtransmitted vibration measurement on the human. Method: To obtain the temporary threshold shift (TTS) in the fingertip vibrotactile perception threshold, the vibrotactile perception thresholds were measured before and after the subjects were exposed to hand-transmitted vibration from the hand-held tool. The vibration magnitude has been measured by using conventional vibration measurement on the tool and by using the proposed consideration vibration on the human simultaneously. Results: The proposed hand-transmitted vibration measurement on the subject was proportional with increasing TTS. In contrast the data from conventional vibration measurement on the tool shows a relatively constant vibration level while TTS increases within a subject group. The proposed measurement method of hand-transmitted vibration on the subject captures at least some of the effects of factors relating to the human interaction with the tool identified within Annex D of the ISO 5349-1 standard. The effectiveness of the proposed hand-transmitted vibration measurement consideration on the human for improved understanding of tool vibration exposure has been shown.
Risks of Occupational Vibration Exposures
2006
In the VIBRISKS project, three experimental studies were designed and conducted with the aim of investigating the acute vascular effects of hand-transmitted vibration in healthy men. Study 1 explored the relation between acute vascular effects and (i) vibration magnitude, (iii) vibration frequency, (iii) exposure duration, and (iv) alternative measures of vibration dose of the general form: dose = a m t n , where a and t are the acceleration magnitude and the duration of vibration exposure, respectively. It was found that a measure of dose that better reflects the digital vasoconstriction following vibration exposure is at (or possibly at 2). The use of at during the day (as well as over years) would make the calculation of 'dose' easier. It would also put more 'weight' on the duration of daily exposures to hand-transmitted vibration than when using the a 2 t relationship underlying the current calculation of the daily A(8). Study 1, moreover, investigated the acute response of finger circulation to vibration with different combinations of magnitude and duration but with the same "energyequivalent" acceleration magnitude according to current standards for handtransmitted vibration. For the range of vibration magnitudes investigated (44 to 176 m/s 2 r.m.s. unweighted; 5.5 to 22 m/s 2 r.m.s. when frequency-weighted according to ISO 5349), the vasoconstriction during exposure to 125-Hz vibration was independent of vibration magnitude. The after-effect of vibration was different for stimuli having the same "energy-equivalent" acceleration, with greater effects following longer durations of exposure. The "energy-equivalent" acceleration failed to predict the acute effects of vibration both during and following vibration exposure. Study 2 compared the acute response of finger circulation to continuous and intermittent vibration having the same total duration of vibration exposure and the same energy-equivalent acceleration magnitude. For the vibration stimuli investigated (exposure durations varying from 1.88 minutes to 30 minutes, with rest periods varying from 1.88 minutes to 15 minutes), the reduction of FBF during exposure was the same for continuous and intermittent vibration. The after-effect of vibration was greater following the continuous vibration exposure. Although some evidence from this study is consistent with intermittent vibration having a less severe effect than continuous vibration, this evidence is not yet conclusive. Study 3 investigated the combined effects of force and vibration on finger circulation. Push forces of three magnitudes (0, 2, and 5 N) and vibration with two frequencies (31.5 and 125 Hz) and two magnitudes (2 and 8 m/s 2 frequency weighted) were used. Modest levels of force applied by a finger had a large effect on the finger blood flow, possibly due to the constriction of local blood vessels. The acute vascular effects of vibration caused additional reductions in finger blood flow that were not limited to the finger experiencing force and vibration. In all fingers (exposed and not exposed to vibration), the greater the magnitude of vibration, the greater the reduction in finger blood flow. In all fingers (exposed and not exposed to vibration), when the vibration was frequency-weighted according to current standards, 125 Hz vibration caused greater reductions in finger blood flow than 31.5 Hz vibration.
Industrial Health, 2012
Standard ISO 5349-1:2001 using the frequency weighting W h . This paper compares eight frequency weightings that might be used to supplement or replace W h . The comparison is based on a data from two databases, one containing over 7200 measured hand-arm vibration (HAV) spectra from a wide range of industrial machines the other recording exposure history and injury for workers referred to the Health and Safety Laboratory. Acceleration spectra from the machinery database are analysed to give weighted values for the alternative frequency weightings. These weighted values are compared and then used to estimate a set of alternative lifetime vibration dose values for subjects in the referral database. Statistical comparison of these lifetime dose values against assessments of hand-arm vibration syndrome (HAVS) and sensorineural HAVS prevalence suggests that values based the two weightings W h and W h50lp (the W h weighing low-pass filtered at 50 Hz) provide the strongest indicators for developing these injuries. For vascular HAVS there was no clear evidence to advocate any individual frequency weighting. For all injury categories the strongest relationships were for the first power of acceleration magnitude.